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Can Japan Burn Flammable Ice For Energy? (cnn.com)
dryriver writes: Japan is a country that currently has to import 90% of its fuels for energy generation, having very little in the way of oil, coal or natural gas reserves in the country. Since the Fukushima disaster, its 50-plus nuclear reactors have been mostly idle. This makes Japan one of the least self-sufficient countries in terms of energy generation in the developed world. But there is an untapped energy resource that Japan has in abundance: ice that has large quantities of methane trapped in it. These ice crystals hold a remarkable quantity of natural methane gas. It is estimated that one cubic meter of frozen gas hydrate contains 164 cubic meters of methane. Japan has so far spent over $1 billion on research and development efforts in order to find a way to efficiently extract the methane from the ice. Where is this methane rich ice located? Engineers have so far focused on Nankai Trough, a long, narrow depression 50 kilometers off the coast of central Japan, which had been extensively surveyed over many years. Analysis of extracted core samples and seismic data has revealed that 1.1 trillion cubic meters of methane -- enough to meet Japan's gas needs for more than a decade -- lies below the floor of the trough. Some experts think that if an efficient method is found to extract methane from flammable ice, it could change the energy map of the entire world. Flammable ice has either been found, or is suspected to be present in large quantities, off the coastlines of all 5 continents in the world (the linked article has a map showing the currently known locations). Ten years from now the price of energy around the world may thus not be set by how much oil, coal or natural gas costs at that point in time, but rather by how much methane extraction from flammable ice costs.
You've vastly underestimated the energy density of methane.
164m3 of methane is about 6GJ of energy (55MJ per kg, 0.656kg per m3, 164m3. 55 * 0.656 * 164 = 5.9GJ)
1 cubie metre of ice, minus the ~100kg of methne is 900kg.
Melting 1kg ice takes 333.5kJ of energy. Melting 900kg of ice takes 300MJ, so there's an excess of about 5.6GJ of energy per cubic metre. That assumes the ice is already at 0 degrees. Add on 3.6MJ per degree below zero to heat up 900kg of ice and 200kJ per degree to heat up 100kg of methane.
Assuming the ice is at -20 degrees, that's another 76MJ, still insignificant compared to the 5.9GJ of energy in the methane.
However, you don't need to burn anything to melt ice. It would take a while, but you can use the energy in the atmosphere to melt it, effectively for free. You can use a heat pump to speed it up, without using as much energy.